In hydraulic valve technology, it is known to provide a chamber with a damping orifice in an area of the spool to improve high frequency valve stability. Typically, in this type of application, a feedback chamber is isolated from the control port via a damping orifice, and out of the normal hydraulic fluid flow path or the utilization of another spool chamber connected via a damping orifice to the first stage outlet port or hydraulic supply port is used. This type of valve configuration can bring about prolonged periods of axial low frequency oscillation of the spool with respect to the valve body. It is desirable to reduce the aforesaid prolonged period of axial oscillations.
Accordingly, it is an object of the invention to provide a proportional pressure control valve having one of the typical damping chamber plus a feedback chamber which is placed in the hydraulic fluid flow path between the control port and the tank port and configured not to inhibit the performance of the valve during a full ON episode and a full OFF episode.
It is a further object of the invention, as aforesaid, to provide a proportional pressure control valve wherein the prolonged period of continuous axial oscillations is eliminated.
It is a further object of the invention to provide a proportional pressure control valve, as aforesaid, wherein during the aforesaid period of axial oscillations, spool movement is arrested reducing oscillatory behavior of the spool.
It is a further object of the invention to provide a proportional pressure control valve, as aforesaid, wherein the aforesaid arrestment of axial oscillations causes an elimination in pressure oscillations.
It is a further object of the invention to provide a proportional pressure control valve, as aforesaid, wherein after the expiration of the period of axial oscillations, spool movement is arrested to maintain the hydraulic level at a pre-determined level.